Fixed clip resize for document.rootScroller with inertTopControls

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp

Index: third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
index 06a015ef2c4a8f2bacf9372b1d4ef78b07dbd2e5..bda59280e6ef8d758d05c0989bc0357085a21380 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -633,16 +633,28 @@ void PaintLayerCompositor::frameViewDidChangeLocation(
     m_overflowControlsHostLayer->setPosition(contentsOffset);
 }
 
+void PaintLayerCompositor::updateContainerSizes() {
+  if (!m_containerLayer)
+    return;
+
+  FrameView* frameView = m_layoutView.frameView();
+
+  // The root scroller must always size to the root FrameView.
+  if (rootLayer() && rootLayer()->isRootScroller())
+    frameView = m_layoutView.document().topDocument().view();
+
+  m_containerLayer->setSize(FloatSize(frameView->visibleContentSize()));
+  m_overflowControlsHostLayer->setSize(
+      FloatSize(frameView->visibleContentSize(IncludeScrollbars)));
+}
+
 void PaintLayerCompositor::frameViewDidChangeSize() {
-  if (m_containerLayer) {
-    FrameView* frameView = m_layoutView.frameView();
-    m_containerLayer->setSize(FloatSize(frameView->visibleContentSize()));
-    m_overflowControlsHostLayer->setSize(
-        FloatSize(frameView->visibleContentSize(IncludeScrollbars)));
+  if (!m_containerLayer)
+    return;
 
-    frameViewDidScroll();
-    updateOverflowControlsLayers();
-  }
+  updateContainerSizes();
+  frameViewDidScroll();
+  updateOverflowControlsLayers();
 }
 
 enum AcceleratedFixedRootBackgroundHistogramBuckets {
@@ -835,12 +847,8 @@ void PaintLayerCompositor::updateRootLayerPosition() {
     m_rootContentLayer->setSize(FloatSize(documentRect.size()));
     m_rootContentLayer->setPosition(documentRect.location());
   }
-  if (m_containerLayer) {
-    FrameView* frameView = m_layoutView.frameView();
-    m_containerLayer->setSize(FloatSize(frameView->visibleContentSize()));
-    m_overflowControlsHostLayer->setSize(
-        FloatSize(frameView->visibleContentSize(IncludeScrollbars)));
-  }
+  if (m_containerLayer)
+    updateContainerSizes();
 }
 
 void PaintLayerCompositor::updatePotentialCompositingReasonsFromStyle(